Improved DFT-based channel estimation for downlink lte system with adding virtual carrier frequency response

Abstract

In Long Term Evolution (LTE) systems, some subcarriers at the borders of the allocated bandwidth are known as virtual subcarriers which are not used for data transmission. Conventional DFT-based channel estimation methods encounter performance degradation due to low SNR and the edge effect caused by virtual subcarriers. Adding virtual carrier frequency responses (VCFR) properly at receivers is proved to be able to effectively mitigate edge effect. The proposed method adopts the VCFR addition method into practical downlink LTE systems to alleviate edge effect. A novel noise eliminating strategy based on energy detection is demonstrated in the proposed method to improve the overall performance especially in low SNR scenario. Compared with existing DFT-based channel estimation methods, simulation results of the proposed channel estimation method showed a relatively lower Mean Square Error (MSE) and raw Bit Error Rate (BER) under several kinds of standard channel models with wide SNR range. The proposed method is also proved to have roughly the same level of complexity as conventional DFT-based channel estimation method.